netdev - [PATCH 0/7] nfc: llcp: fix and improvements

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Date:   Sat, 15 Jan 2022 13:26:43 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, linux-nfc@...ts.01.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 0/7] nfc: llcp: fix and improvements

Hi,

Patch #1:
=========
Syzbot reported an easily reproducible NULL pointer dereference which I was
struggling to analyze:
https://syzkaller.appspot.com/bug?extid=7f23bcddf626e0593a39

Although direct fix is obvious, I could not actually find the exact race
condition scenario leading to it.  The patch fixes the issue - at least under
my QEMU - however all this code looks racy, so I have a feeling I am plumbing
one leak without fixing root cause.

Therefore I would appreciate some more thoughts on first commit.

The rest of patches:
====================
These are improvements, rebased on top of #1, although should be independent.
They do not fix any experienced issue, just look correct to me from the code
point of view.

Testing
=======
Under QEMU only. The NFC/LLCP code was not really tested on a device.

Best regards,
Krzysztof

Krzysztof Kozlowski (7):
  nfc: llcp: fix NULL error pointer dereference on sendmsg() after
    failed bind()
  nfc: llcp: nullify llcp_sock->dev on connect() error paths
  nfc: llcp: simplify llcp_sock_connect() error paths
  nfc: llcp: use centralized exiting of bind on errors
  nfc: llcp: use test_bit()
  nfc: llcp: protect nfc_llcp_sock_unlink() calls
  nfc: llcp: Revert "NFC: Keep socket alive until the DISC PDU is
    actually sent"

 net/nfc/llcp.h      |  1 -
 net/nfc/llcp_core.c |  9 +-------
 net/nfc/llcp_sock.c | 54 ++++++++++++++++++++++++---------------------
 3 files changed, 30 insertions(+), 34 deletions(-)

-- 
2.32.0